The kingpin of standardized semi-trailers is designed to engage removably on a fifth wheel carried by a towing vehicle in order to form a pivot link allowing semi-trailers to be moved by the towing vehicle associated therewith.
Patent EP 1,874,607, in the applicant's name, teaches a system for locking the kingpin of a semi-trailer on a railway unit wherein a cowling part is mounted, via a central opening, on the kingpin of the semi-trailers in order to be received in a receiving element, called nacelle, that is mounted on the railway unit. This nacelle is in particular intended to automatically center and lock the cowling part, and therefore the kingpin, when the cowling part is received within the nacelle. This nacelle is typically actuated by a lifting means allowing it to be moved vertically in order to receive the cowling part and the kingpin for maintaining and locking thereof.
In case of collision of the railway unit carrying the semi-trailer, or during other events, an abrupt impact may be transmitted to the kingpin by the locking system. While the locking system of the applicant satisfies railway standards, it is not damaged by such an impact, which may correspond to a force of several tens of tons. At the cowling part, however, this impact may damage the kingpin, since the latter satisfies road standards, which are less demanding than railway standards on this point.
Such damage to the kingpin is not easily detectable. Thus, after a violent impact during collision, a kingpin may be made fragile without this fragility being detected. Unaware of this fragility, the driver then unloads the semi-trailer from the railway unit to take it to its final destination by pulling it with his tractor vehicle. During this travel, the fragile kingpin may break, which may have drastic consequences.
There is therefore a need for an impact detection device that makes it possible to detect whether a railway unit carrying the semi-trailer has undergone an impact that could damage the kingpin. Such an impact detection device must advantageously be able to be calibrated to be triggered beyond a predetermined threshold.
According to operating requirements, this threshold may be modified to make it possible to detect smaller impacts, in particular out of a concern for protecting transported goods, or more importantly, for example in the case of different railway standards.